The present invention relates to improved digital circuits for automatically tracking particles moving across a video image in the form of signal dots, and determining their velocity or velocity distribution. The video image is detected by an electronic camera and the video camera output is electronically processed.
A circuit arrangement of a similar type is disclosed in German Pat. No. 2,905,118 which corresponds to U.S. Pat. No. 4,238,767. However, this earlier circuit is more complicated and not suitable for measuring particle mixtures having an inhomogeneous velocity distribution. Additionally, dot-by-dot tracking of particles cannot be performed by this earlier circuit.
It is an object of the present invention to improve the above-mentioned circuit arrangement in such a way that it is possible to track individual particles in the video image to determine their velocities or velocity distribution, particularly for particles moving in sedimentation cells.